the weather tonight and the new threat of flash floods in the west, weather moving from one extreme to another, bone dry land and towns washed away by walls of water. Reporter: The Dallas area today got served texas-sized traffic nightmares. Nearly a foot of rain in just six hours near valley view. Drivers had to be rescued. Others abandoned their cars. Flooded roads shut traffic down for miles. At this store, you had to slosh to shop. Another round of it, so it may be pointless to even start cleaning at this point. Reporter: They are cleaning up in Colorado tonight. Rain-flooded streets and soaked restaurants. Hail blasted car windows. Lost my back window. Reporter: Sirens warned people to get to higher ground. This really gives you an idea of the power of water. Yesterday this channel was empty. There was only dirt here. But the blood waters brought all of these giant Boulders and rocks down stream. This was manitou springs two years ago. This time the waters were tamed by a $4 million project that's not even finished yet, including this 20-foot high wall, meant to steer the deluge away from neighborhoods. We're extremely happy. Considering that the project is not completely built and what it did last night in protecting homes. Reporter: That was good news to Nellie and John Webster. They've watched their town endure a few too many fires and mud slides. A couple years have been humdingers. Reporter: Tonight there are still flash flood watches in parts of Texas, Oklahoma and Arkansas. David. . There's a state of emergency in the pacific northwest as two

This transcript has been automatically generated and may not be 100% accurate.

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